This invention relates to assistive devices, and more particularly to a walker with a U-shaped lower frame, a plurality of wheels fixed with the U-shaped lower frame, a U-shaped upper frame, generally vertical left and right double scissor mechanisms interposed between the U-shaped lower frame and the U-shaped upper frame that hold the U-shaped lower frame in alignment with the U-shaped upper frame, and a linear actuator; and where the walker is adapted to provide motorized height adjustment capability, increased independence and range of activity, increased safety when sitting or standing (especially for persons with subnormal leg muscle strength or balance difficulties), and a minimized storage and transportation footprint. The prior art includes: U.S. Pat. No. 2,020,766A (Nov. 12, 1935); U.S. Pat. No. 2,645,538A (Jul. 14, 1953); U.S. Pat. No. 2,738,830A (Mar. 20, 1956); U.S. Pat. No. 3,840,034A (Oct. 8, 1974); U.S. Pat. No. 4,019,756A (Apr. 26, 1977); U.S. Pat. No. 4,123,078A (Oct. 31, 1978); U.S. Pat. No. 4,249,749A (Feb. 10, 1981); U.S. Pat. No. 4,342,465A (Aug. 3, 1982); U.S. Pat. No. 4,621,804A (Nov. 11, 1986); U.S. Pat. No. 4,770,410A (Sep. 13, 1988); U.S. Pat. No. 4,799,700A (Jan. 24, 1989); U.S. Pat. No. 4,822,030A (Apr. 18, 1989); U.S. Pat. No. 5,033,758A (Jul. 23, 1991); U.S. Pat. No. 5,123,665A (Jun. 23, 1992); U.S. Pat. No. 5,217,033A (Jun. 8, 1993); U.S. Pat. No. 5,244,443A (Sep. 14, 1993); U.S. Pat. No. 5,366,231A (Nov. 22, 1994); U.S. Pat. No. 5,538,268A (Jul. 23, 1996); U.S. Pat. No. 5,727,800A (Mar. 17, 1998); U.S. Pat. No. 5,732,961A (Mar. 31, 1998); U.S. Pat. No. 5,813,720A (Sep. 29, 1998); U.S. Pat. No. 6,120,045A (Sep. 19, 2000); U.S. Pat. No. 6,170,840B1 (Jan. 9, 2001); U.S. Pat. No. 6,231,056B1 (May 15, 2001); U.S. Pat. No. 6,494,815B1 (Dec. 17, 2002); U.S. Pat. No. 6,675,820B2 (Jan. 13, 2004); U.S. Pat. No. 6,948,727B1 (Sep. 27, 2005); U.S. Pat. No. 7,055,847B2 (Jun. 6, 2006); U.S. Pat. No. 7,156,465B2 (Jan. 2, 2007); U.S. Pat. No. 7,237,844B2 (Jul. 3, 2007); U.S. Patent Application No. 2007/0163633A1 (Jul. 19, 2007); U.S. Patent Application No. 2010/0170546A1 (Jul. 8, 2010); U.S. Patent Application No. 2011/0067740A1 (Mar. 24, 2011); U.S. Patent Application No. US 2011/0241303A1 (Oct. 6, 2011); U.S. Patent Application No. 2011/0260421A1 (Oct. 27, 2011); U.S. Pat. No. 8,162,333B1 (Apr. 24, 2012); U.S. Pat. No. 8,215,652B2 (Jul. 10, 2012); U.S. Patent Application No. 2012/0215408A1 (Aug. 23, 2012); U.S. Pat. No. 8,251,380B2 (Aug. 28, 2012); U.S. Patent Application No. 2012/0274037A1 (Nov. 1, 2012); U.S. Pat. No. 8,333,208B2 (Dec. 18, 2012); U.S. Patent Application No. 2012/0318587A1 (Dec. 20, 2012); U.S. Pat. No. 8,562,007B2 (Oct. 22, 2013); U.S. Pat. No. 8,646,804B2 (Feb. 11, 2014). It is desirable to have an improved cart that is superior to any that is disclosed or suggested in the identified references.